In T 112/89 the board stated that, regarding the due care required by Art. 122(1) EPC 1973, the obligations of the applicant and those of his representative were clearly distinct and that the due care to be exercised by the representative might depend on the relationship which existed between him and his client. The board noted that it was clear that both the representative and the applicant had to exercise all due care in order to observe all the time limits during patent granting procedures. In the case at issue, the board was not convinced that the duty of the representative was fully discharged when he had notified his client that a time limit was to be observed and was satisfied that the client had received the notification. On the contrary, when a representative had been instructed to lodge an appeal and did not receive in due time from his client the necessary additional instructions he needed to discharge his duty, he should take all necessary measures to try to obtain from his client these instructions.

In T 1401/05 (20.9.2006) the board stated that the communication between the representative and his client (patent applicant) had worked efficiently. The representative was therefore entitled to rely on his client's awareness of the expiry of the time limit. The representative was not required to issue a further reminder to meet his obligations of due care.

In T 1289/10 the board held that if a European representative provided a contact email address for all kinds of mail, including mail that may require immediate action by the representative, it was essential to perform a mail check at least at the end of each business day. Given the known problem that legitimate mail from time to time was wrongly marked as a possible threat it was evident that this check must include the quarantine area of the email system.